Masculinity matters (but mostly if you’re muscular): A meta-analysis of the relationships between sexually dimorphic traits in men and mating/reproductive success

Humans are sexually dimorphic: on average men significantly differ from women in body build and composition, craniofacial structure, and voice pitch, likely mediated in part by developmental testosterone exposure. Hypotheses which attempt to explain the evolution of dimorphism in humans, such as the immunocompetence handicap hypothesis and the male-male competition hypothesis, assume that more dimorphic (i.e. masculine) men have historically achieved greater mating success, resulting in greater reproductive success. This is either because women select more masculine men due to their greater immune function, because more masculine men expend more energy on mating effort, or because more masculine men out-compete their rivals for other routes to mating success. Thus far, however, evidence for an association between masculinity and reproductive success is unclear. We conducted the most comprehensive meta-analysis to date, on the relationship between masculinity in six domains (faces, bodies, voices, height, digit ratios, and testosterone levels) and mating/reproductive success, comprising 434 effect sizes from 91 studies (total N = 155,348). Body masculinity, i.e. muscularity and strength, predicted both mating and reproductive success. Voice pitch, height, digit ratios and testosterone levels all predicted mating but not reproductive outcomes. Facial masculinity did not significantly predict either. Our findings support arguments that muscularity/strength can be considered sexually selected in humans, but raise concerns over other forms of masculinity, most especially facial masculinity. We are also constrained by lack of reproductive data, particularly from naturally fertile populations. Our data thus highlight the need to increase tests of evolutionary hypotheses outside of industrialised populations.